Summa is a great make of cutter, as is Graphtec and Roland etc. I have used them all over the years…
Buying any cutter or printer is like buying a used car. Might look great, but means nothing. its how it has been treated long term and what’s going on under the hood, so to speak.
At the end of the day, you may get a great cutter at a brilliant price. but that’s pretty much down to luck!
Personally, I would advise you to buy the best you can afford! Do not scrimp on your cutter if that’s what is bringing in the “bread and butter” jobs on a daily basis.
I always buy wider than I really need, it means if you have a printer or cutter, you can add it without being limited on contour cutting at 54 or 60 inches wide. It allows you to plot much wider than having join tiles etc
A common issue overlooked is tracking and easy setup and alignment of vinyl in your machine. more so on used machines because pinch wheels, grit rollers etc become worn etc which has adverse effects on accurate cutting and tracking of long cuts/prints.
If you are contour cutting prints, make sure you get plenty test print and cuts done to make sure that works properly too. I bought the top of the range Summa cutter with automated takeup real for roll to roll cutting, from Perfect Colours, only for it to go back for a refund after months of complaints due to being faulty and that was brand new! So it’s not just used machines that can have glitches and I don’t just mean Summa, just coincidental my issue was with one.